As described in JP 7-33060 A, in a three-wheeled vehicle (a vehicle in which a front wheel or a rear wheel is considered as one wheel) according to the related art, a platform on which a driver rides is fixed to a body frame. When such a three-wheeled vehicle goes around a curve at a high speed, a centrifugal force acts to significantly tilt the “one wheel”. This phenomenon is caused for all the three-wheeled vehicles according to the related art that are commercially available (see J. Alderson and D. Rushton “MORGAN Sweeps the Board The Three-wheeler Story”, 1978, published by Gentry Books Limited, 16 Regency Street, London SW1 and “MORGAN Three-Wheelers Ultimate Portfolio 1909-1952”, published by Brooklands Books Ltd. P.O. Box 146, Cobham, Surrey, KT11 1LG. UK).
In contrast, in heavy trucks with suspensions in which the left and right wheels share an axle (so-called rigid-axle suspensions or De Dion-axle suspensions), the left and right wheels are not inclined even if the vehicle body is tilted.
JP 2004-123080 A describes a three-wheeler in which a body frame having wheels thereon and a platform (a structure to which a seat is mounted) on which a driver rides are integrated with each other. A connecting structure configured to connect the platform and the body frame to each other as described in JP 2004-123080 A is a rigid connecting structure. During cornering, the three-wheeler according to JP 2004-123080 A utilizes positive camber thrust (camber thrust obtained by tilting tires on the two rear wheels) obtained by rolling in the direction opposite to operation of common four-wheelers and three-wheelers.
JP 9-86448 A describes a connecting structure in which six hydraulic actuators are disposed between a vehicle frame and a cab and the six hydraulic actuators are driven to improve vibration characteristics with six degrees of freedom. In the connecting structure described in JP 9-86448 A, the six hydraulic actuators are controlled based on complicated computation to improve the vibration characteristics of a rolling motion, a pitching motion, a bouncing motion, a longitudinal motion, a lateral motion, and a yawing motion of the platform.